2017: Pre-debut In 2017, Jongho was introduced as one of the trainees from
KQ Entertainment on the
JTBC survival reality show
Mix Nine. He was eliminated in the tenth episode with a final ranking of 43.
2018–present: Debut with Ateez On October 24, 2018, Jongho officially debuted as the main vocalist of KQ Entertainment's first boy group
Ateez with the debut EP
Treasure EP.1: All to Zero. Under the group's name, Jongho has performed two solo songs, "Everything", which he co-wrote as a part of Ateez fourth studio album
The World EP.Fin: Will, and "To be your light" from the album ''
Golden Hour: Part.3 'In Your Fantasy Edition'.''
2020–present: Solo activities and actor debut From May 2020 to May 2022, Jongho released covers of Korean drama original soundtracks under the project name "JJongST" (). The music videos accompanying the covers feature Jongho visiting and singing at the location where the respective dramas are shot. Other than JJongST, Jongho also released other covers including "Wild Flower" by
Park Hyo-shin, "
Ditto" by
NewJeans with Maddox, "Dear Name" by
IU with Ateez's San, and "Tell Me That You Love Me" by James Smith. In 2021, Jongho debuted as an actor in the
KBS2 drama
Imitation with the role Hyuk, the youngest member of a fictional group Shax. In the same year, he released the soundtrack titled "Gravity" for the drama
Reborn Rich. In February 2023, Jongho released the soundtrack for the historical drama
Our Blooming Youth titled "Wind". In May 2023, Jongho took part in
Immortal Songs: Singing the Legend and performed the song "So You" by Yarn. From November 2024 to January 2025, Jongho appeared on
KBS2 Moving Voices in Munich, Germany alongside
Hongjoong,
Bae Suzy,
Henry Lau,
Sunwoo Jung-a, and
Sohyang. On December 14, 2024, Jongho collaborated with
STAYC's
Sieun for a duet performance of "When It Snows" by
Lee Mu-jin for the 2024 Music Bank Global Festival in Japan. On April 7, 2025, Kwon Soon-kwan of the South Korean indie band No Reply released the digital single "Our Memories" () featuring Jongho. In August 2025, Jongho released the soundtrack "Just like the First Time" () for the drama
The Nice Guy. In October 2025, Jongho appeared in
KBS2 The Seasons to perform "
Good Day" by
IU and "Because you're my woman" by
Lee Seung-gi. In December 2025, Jongho released the music video for his solo song "To Be Your Light". ==Personal life==